--deep (-D)
When used in conjunction with --update, this flag forces emerge
to consider the entire dependency tree of packages, instead of
checking only the immediate dependencies of the packages. As an
example, this catches updates in libraries that are not directly
listed in the dependencies of a package.

--deep (-D)
When used in conjunction with --update, this flag forces emerge
to consider the entire dependency tree of packages, instead of
checking only the immediate dependencies of the packages. As an
example, this catches updates in libraries that are not directly
listed in the dependencies of a package.